COGNITIVE & NOOTROPIC
Semax vs. Selank vs. DSIP: A Structured Comparison
Six dimensions, three peptides — a reference table for the key variables that distinguish these neuroactive research compounds.
The short version
Three peptides, three different approaches to brain health. Semax targets growth-factor upregulation and neuroprotection. Selank targets anxiety relief through GABAergic modulation. DSIP targets sleep architecture through a mechanism no one has fully resolved. They share a common pattern: deep preclinical rodent files, geographically narrow or very sparse human data, and no Western regulatory approval. The table below maps the variables that matter most when reading across their evidence bases.
Comparison table
| Dimension | Semax | Selank | DSIP |
|---|---|---|---|
| Peptide class | Synthetic ACTH(4-10) analog; heptapeptide | Synthetic tuftsin analog; heptapeptide | Endogenous nonapeptide; no synthetic modification |
| Most studied in | Neuroprotection (ischemia/stroke), cognitive impairment, spinal cord injury [1][2][5] | Anxiety-asthenic disorders, GABAergic modulation, stress models [8][9][12] | Sleep disorders, HPA-axis modulation, longevity (murine) [14][15][17] |
| Evidence base (model) | Predominantly rodent; limited Russian/Ukrainian clinical studies; one 2025 SCI mouse study | Predominantly rodent; limited Russian clinical studies in anxiety patients; one human immunomodulation study [12] | Predominantly rodent; two small 1980s human pilots [16][17]; one 2024 murine BBB-fusion study [13]; 2006 critical review concludes evidence is weak [14] |
| Administration studied | Intranasal (primary in rodents and Russian clinical practice) | Intranasal (primary); subcutaneous in some rodent work | Intravenous in human pilots [16][17]; intranasal in community use (not formally studied) |
| Regulatory status | Rx drug in Russia/Ukraine; unscheduled research chemical in US; not FDA/EMA approved | Registered anxiolytic in Russia; research chemical in US; not FDA/EMA approved | Never approved or marketed by any regulator; INN = emideltide; research chemical only |
| Key caution | Neurotrophin/gene-expression scope is broad and not trivial; most evidence is single-region and Russian [3][2] | Multi-system (GABAergic, opioid, immune) interaction unknowns; non-response is common | No receptor identified after 40+ years [14]; large non-response rate; mechanism-based interactions unpredictable |
Peptide class and lineage
Semax and Selank are both synthetic heptapeptides engineered from natural fragments, with the same C-terminal Pro-Gly-Pro metabolic-stabilization motif. Semax derives from a fragment of ACTH, the pituitary stress-response hormone. Selank derives from tuftsin, an immune-signaling tetrapeptide from IgG. Both lose the parent molecule's most potent or problematic effects while retaining a defined pharmacological window. DSIP is different: it is an endogenous peptide — the body makes it naturally — which is why its study began with isolation from biological fluid rather than synthesis from a hormone fragment.
Evidence base and geographic concentration
All three share a geographic concentration that reviewers flag as a limitation. The bulk of Semax and Selank clinical evidence originates from a handful of Russian research institutions; much of it is published in Russian-language journals and has not been independently replicated in Western RCTs. DSIP's 1980s human pilot work came from European groups, and the 2024 BBB-fusion study from a Chinese group, but modern controlled trials in any of these peptides are essentially absent.
This matters for interpretation. A coherent rodent mechanistic story plus a small regional clinical dataset is a meaningful signal, but it is not the same as a Phase 3 trial. All three should be described as investigational rather than established in human use.
Mechanisms and what separates them
The distinguishing mechanistic signatures:
- Semax — BDNF/NGF upregulation (rapid, region-specific [3][4]) + enkephalinase inhibition in human serum [7] + broad immune/vascular gene-expression shifts in injured rodent brain [2]. Its nootropic rationale is growth-factor-forward.
- Selank — Positive allosteric GABA receptor modulation (distinct from benzodiazepines [8]) + GABA gene expression shifts in frontal cortex [10] + BDNF upregulation in hippocampus [11] + Th1/Th2 cytokine modulation [12]. Its anxiolytic rationale is GABAergic-forward with neurotrophin and immune dimensions.
- DSIP — No identified receptor; putative BBB transporter; documented ACTH suppression in human plasma [16]; parabolic dose-response. The least understood of the three.
The practical implication: Semax and Selank are plausible (if unproven in Western RCTs) tools for different cognitive dimensions; DSIP is the most uncertain, with the highest non-response rate and the fewest mechanistic handles.
Regulatory and sourcing context
None of the three is approved by the FDA or EMA. Semax and Selank have prescription-drug registration in Russia, which means they have a regulatory track record of at least some structured clinical oversight in that context — a meaningful distinction from a pure research-chemical designation. DSIP has never been approved or marketed by any regulator in any form.
In the United States all three are sold as unregulated research chemicals. There is no required testing of identity, purity, sterility, or dose accuracy for material sold through those channels. The pharmacology published in peer-reviewed journals was conducted in pharmaceutical-grade or laboratory-synthesized material, not consumer research-chemical product — a gap that matters for any safety or efficacy inference.